Parasites of the genus Plasmodium are responsible for 300-500 million cases of human malaria and cause about one million deaths every year. The search for new novel antimalarials relies on a number of approaches including natural products, high-throughput screens, small chemical libraries directed at important pathways, or just structural modification of previously active antimalarials. Prioritization, optimization, and advancement of a good experimental antimalarial to a clinically useful drug may be greatly facilitated by knowledge of the target or the pathway. Chemistry and Chemical Biology based approaches can be powerful for target identification and validation, especially when tightly linked to open-ended biological tools. We will study the Structure Activity Relationships (SAR) of select bioactive molecules. For each compound class, we will (i) establishment isogenic sensitive and resistant strains to help develop confidence in the chemistry-biology links, before genomic DNA sequencing on the isogenic strains for each chemical classes (ii) separately, develop a ligand-binding proteomics approach to identify drug targets. To gain confidence in our approach, we will use escalating challenge in our specific aims. In Specific Aim 1, to establish a well-grounded set of protocols, we will first establish and validate genome-sequence and proteomics- based approaches for target identification, using new antimalarial chemicals from our team with proven targets. In Specific Aim 2, our genome-wide target identification approaches will be expanded to new anti-metabolites where the mechanisms of action are different and unknown, compared to what was expected. In Aim 3, we will apply the genomic tools to completely new antimalarials whose mechanisms of action are completely unknown. Together, these carefully developed and controlled studies, involving small chemical molecules and genomic tools, will lead to generally applicable, streamlined approaches for establishing connections between good antimalarials and their high-value targets in the parasite.